


Burn

by anakien



Category: Death Note & Related Fandoms, Death Note (Anime & Manga)
Genre: AU, Alternate Universe - Yagami Light Is Not Kira (Death Note), Ambiguity, Gen, Inspired by Hamilton, L definitely demonstrates his moral ambiguity here, Minor L/Yagami Light, Sayu is smarter than she lets on
Language: English
Status: Completed
Published: 2020-07-07
Updated: 2020-07-07
Packaged: 2021-03-05 05:40:43
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,286
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25129438
Author URL: https://archiveofourown.org/users/anakien/pseuds/anakien
Summary: Sayu notices something strange about Light's new friend Ryuzaki.
Relationships: L & Yagami Light, Yagami Light & Yagami Sayu
Comments: 28
Kudos: 204





	Burn

**Author's Note:**

> Back with another Death Note fic! This is in honor of Hamilton getting released on Disney+ last week. The idea specifically comes from "First Burn" - one of the Hamildrops. "First Burn" was LMM's original draft idea for the song "Burn" where Eliza was a lot angrier about Alexander's infidelity. I actually like it more than "Burn" itself! Either way, the lyrics that sparked this idea are as follows:
> 
> "I know about whispers
> 
> I see how you look at my sister"
> 
> Essentially, this is an AU where L pretends to date/befriend Light in order to observe him/the Yagami family on suspicion of being Kira. Sayu notices something is up.
> 
> I don't own the lyrics or Death Note. Enjoy!

When Sayu first hears that Light was bringing home a friend, she's thrilled. Her brother has never really shown much interest in people - in dating or in just plain, normal friends. He's boring - all he does is study all day.

She's sitting in the kitchen one day after school, chatting with Mom and procrastinating doing her math homework. In the other room, the front door opens and closes.

"In here, Light," Mom calls out. She turns from the stove and smiles at him when he walks in. "How was school today?"

"Same as ever," Light says. "How was your day?" They make smalltalk for a few minutes, which is the first sign that Light wants something. Normally whenever he first gets home, he immediately heads to his room. Light has never much been one for idle conversation, something always deemed as unnecessary in his eyes.

Sayu may not be as smart as her brother, but she's always been really good at reading people.

Light clears his throat after a while and slings his backpack further up on his shoulder. "So, Mom. Do you mind if I invite a friend over for dinner this weekend?"

"A friend?" Sayu says, finally looking up her work in interest. Here we go, something interesting. "Light finally has a girlfriend?"

Light narrows his eyes at her. " _He_ is most definitely not my girlfriend. His name is Ryuzaki."

Mom clasps her hands together. "I don't see why not," she says. "Your father won't be here. He's already told me his schedule is hectic for the next couple of weeks."

Light doesn't look like he cares much about that, but he still politely expresses his sadness at the fact.

"Is he cute?" Sayu asks, solely to watch an exasperated look flit across Light's face. Also, because all of her friends would be so jealous to hear she's dating a college boy. And he must be something special if Light's deemed him worthy enough to bring over.

"I don't particularly want to answer that," he says, scowling at her. Then, an uncomfortable, almost guilty expression flits across his face so briefly that Sayu almost questions whether or not it really happened.

"Oh, Light, it'll be so nice to finally meet some of your college friends," Mom says. "What do you want me to fix?"

"Well, he really likes anything sweet, so he probably won't care about dinner so much as the dessert." Light's responding smile is fond, which Sayu thinks is kinda weird. "Thanks for doing all of this, Mom. I'll be sure to invite him over tomorrow during class."

Sayu waits until she hears the click of Light's door shutting at the top of the stairs before she turns to Mom and raises an eyebrow.

"Don't you think that was kinda weird?" she says.

"Why would it be weird?" Mom wipes her hands on her apron and picks up a knife to start dicing vegetables. She lines up the carrots neatly and starts to cut.

"He never brings anybody home," Sayu whispers. "Ever."

"Well, I will admit that it's a little out of the ordinary. But he's been so much happier lately," Mom says, wiping her forehead with the back of her hand. "Maybe Ryuzaki has been the cause of that."

Sayu considers this for a moment. Light's nervousness at asking, his guilty expression, the fond smile...

"Oh," Sayu says, everything clicking into place. Light has a crush! Her practically abstinent brother was finally braving the dating waters. Maybe... Or he just didn't really know how to act around a new close friend. With Light, it could be either one.

"Don't worry, Mom," Sayu promises. "I'll be on my best behavior."

\---

Over the next couple of days, Sayu tries to look up this Ryuzaki on the internet. But it's actually pretty hard to do that for two reasons - one, because Light didn't tell them his last name, and two, because apparently Ryuzaki is a ridiculously common name for boys Light's age. Ugh.

Even Light is pretty tight-lipped about him when she asks. He probably thinks she's still trying to see if he's cute or not, so he shuts down every question she has.

In the end, all she knows is that he's another student at To-Oh, and that he's also studying Criminal Justice, just like Light, but that's pretty much it.

He must be something special, if Light's bringing him home.

\---

On Friday night, Light bustles around the house with a flurry of nervous energy. Her usually calm, cool, and collected brother is visibly nervous, straightening objects in their living room and making their placemats even in the kitchen.

Sayu is fascinated by it. She and Mom keep exchanging wide-eyed looks when Light's back is turned. She puts on a nice shirt and pulls her hair up. Light smiles at her approvingly when she comes back downstairs.

"What time is he supposed to arrive?" Sayu asks. She peeks out the curtains in the front and jerks back when a limo pulls up. "Uh, Light?"

He walks up behind her and looks over her shoulder. He smiles, and some of the tension bleeds out of his shoulders.

"That's him." He looks down at her and waves her away. "I'll let him in, go help Mom."

Sayu turns and leaves the room, but instead of heading to the kitchen, she runs up the stairs to her room and climbs on her bed to look out her window.

It's just in time, too, as the limo is driving off, and Ryuzaki is walking down the front path. She can't see his face, but she can see a mop of dark hair and a hunched figure with hands shoved in his pockets. He disappears under the porch awning, and then she can hear Light's voice welcoming him downstairs.

Suddenly nervous, she sits up and climbs down the bed, tugging her skirt down straight.

"Sayu! Come meet Ryuzaki."

Taking a breath, she walks downstairs, nearly stopping in her tracks when she finally sees his face. Wide, almost black eyes scrutinize her with every step she takes. She was right - his hair is dark, just as black as his eyes - and he has an almost disheveled appearance.

This was _not_ what she was expecting from Light.

She finally makes it to the bottom of the stairs and stands next to Mom, who has already been introduced. He smiles at her, and she smiles back, still a little shocked.

"Ryuzaki, this is my younger sister Sayu," Light says.

"Hi, Ryuzaki," she says, bowing towards him. "It's nice to finally meet you. Light's been talking about you all week!"

"Sayu!" Light hisses.

Ryuzaki gives a low chuckle, casting an appraising eye over her brother. "It's nice to meet you too. I have also heard a lot about you." He turns towards their mom and inclines his head. "Thank you for inviting me over, Mrs. Yagami."

"Of course, I was so excited to hear that Light wanted to bring home one of his friends. Come, take off your shoes. Let's move to the kitchen. Dinner is ready!"

Sayu follows Mom towards the kitchen. Behind her, she can hear Ryuzaki whisper to Light, "Interesting, Light, you've been talking about me all week?" and Light's small laugh in return.

It's almost cute. A little awkward to overhear from your cringy older brother, but still cute.

She trots into the kitchen and helps Mom serve dinner. Ryuzaki sits next to Light at the table, sitting with his knees up under his chin. Mom eyes him a little warily after that, but still serves dinner with a smile.

She sits across from him and smiles, determined to learn more about him.

"So," she says once they're all seated, "how did you two become friends?"

"Light and I are in several of the same classes this semester." Ryuzaki holds his fork with only two fingers and spoons his vegetables on it carefully. He brings it up to his mouth and takes a tiny bite. "Your brother very much enjoys criticizing my answers in class."

Light snorts at that. "If I remember correctly, you were actually the first to correct me, after all."

Ryuzaki mumbles something under his breath. "Yes, well, you certainly deserved it."

Light rolls his eyes. "After that, he challenged me to a game of tennis. Which I won, for the record."

Mom perks up at that. "Ryuzaki, you play tennis?"

"I played in junior high."

"Apparently he was one of top-ranked students in England at the time!" Light says.

"Wow, Light, just like you! You two seem to have a lot in common."

"In many ways," Ryuzaki says quietly. "In other ways we are nothing alike at all."

 _What a weird thing to say_ , Sayu thinks, and she can't help but frown a little bit at him. Ryuzaki innocently takes another bite of his vegetables.

"Why don't you tell me more about your family," Ryuzaki says to their mother. "I would very much like to learn more about each and every one of you."

\---

Sayu doesn't know what it is, but there's something about Ryuzaki that doesn't seem to fit.

He's definitely weird. He holds his fork by the tip, leaving it teetering with every movement. It bothers her a little bit how their family all dressed up, but he shows up casually in a cotton shirt and jeans. And the way he sits - hunched over like a frog, with his bare feet on their chairs.

Her dad would've had a heart attack if he'd been home.

Oh, he's polite to their mother, he eats what's put in front of him (and three separate helpings of dessert, which Sayu can't help but wrinkle her nose at), and he's witty, meeting all of Light's sarcastic comments with ease. It's not hard to see why Light likes him so much - he's finally got someone whose mind matches his own.

But something's off.

Sayu has _always_ been really good at reading people.

She watches Light when his attention is focused on Ryuzaki. His eyes have a certain spark to them that hasn't been there before. And he does a pretty good job at hiding it, but there's almost a glow to him when they bicker. Regardless of whether Ryuzaki is just his friend (or even more, she'll concede), he seems almost head over heels for this relationship.

She also watches Ryuzaki when he's looking at Light. More specifically, while he's watching Light when Light's unaware. It doesn't happen often. But when it does, the mask drops. Ryuzaki's friendly and eccentric appearance is replaced by something dark, narrowed eyes and an intensely focused look. It's not hatred, but it's not neutrality, either. And then Light will turn back to catch his gaze, and the mask is back.

It kind of skeeves her out. She keeps looking at her mom, but besides the glances over some of Ryuzaki's weird quirks, she doesn't seem to notice anything out of the ordinary. And Light just seems so thrilled to have someone at his level that if he notices anything weird, he doesn't let on.

Light laughs loudly at something Ryuzaki says, startling her out of her thoughts. When Sayu blinks to shake herself back to the present, she meets Ryuzaki's gaze lying steadily on her.

"Here, I'll be right back," Light says. "I'm going to run upstairs now for a moment. I'll leave you two to talk for a moment."

Mom is cleaning up in the kitchen, and she, Light, and Ryuzaki had moved into the living room to keep talking. It's just her and Ryuzaki left, and as soon as Light leaves, Ryuzaki turns his intense gaze onto Sayu.

She can't just sit there and say nothing about his weirdness. "I don't think I like you," she says. "I don't know if you're good for Light."

Ryuzaki doesn't really react to that, besides the lifting of one eyebrow. If anything, he almost looks a little amused. "What makes you say that?"

"I see how you look at my brother. I don't like it - you look at him like he's something to toy with."

"Your brother is not as innocent as he may seem to you, Sayu," Ryuzaki says, not unkindly.

What the hell is that supposed to mean?!

She narrows her eyes. This is only confirming her suspicions. "I don't have to like you, but I will put up with you because you seem to make my brother happy. But if you break his heart, I'll kill you myself." She vows this. Light's always looking out for her. It's her turn to do the same.

"I see." Ryuzaki's eyes narrow imperceptibly, and he taps his thumb to his mouth. "Perhaps I've been looking into the wrong Yagami all along," he mutters to himself, almost too quietly for Sayu to hear.

Light comes back into the living room at that moment and plops back down onto the couch next to Ryuzaki. "So, how are you two getting along now?"

"Excellent, of course," Ryuzaki lies smoothly, turning towards Light. "We have discovered we are both fans of the latest Hideki Ryuga movie. Isn't that right, Sayu?"

 _How did he know I like his movies?_ Sayu thinks to herself, more than a little unnerved at this whole interaction. _I didn’t say a word about them. Maybe Light said something to him before about it?  
_

“Sayu?” Light prompts, looking at her like she’s lost her mind.

"... That's right," she says after a beat.

Light studies her for a moment and shrugs off her pause. He reclaims Ryuzaki's attention, and Sayu is left to sit, observe, and occasionally chime in.

This isn't over. She'll be watching Ryuzaki. Light will thank her for it one day.

**Author's Note:**

> This was meant to be a one-shot, but there's two ways this story could go:
> 
> 1\. Light is aware that "Ryuzaki" isn't who he says he is and is equally using him to get close and learn more about L.
> 
> 2\. Light isn't Kira and is accidentally caught in the crossfire of the Kira case. (Which means when he founds out that L lied to him about both his identity and the real reason for their relationship/friendship, he is heartbroken and PISSED).
> 
> I'll let y'all pick which one sounds more heartbreaking/compelling for this AU ;)
> 
> Please R&R! I would love feedback.


End file.
